They prescribe it to kids because it stays in your body for a while, so you don't get withdrawal symptoms after skipping one day (because kids are expected to be irresponsible when taking medications). It's also been on the market the longest--and seems safe--so that helps as well.

It's not the most selective (toward serotonin) of the SSRIs. I'm not sure how one would go about precisely quantifying its strength. The newer SSRIs were developed partly to try to avoid some of the side effects of Prozac. The side effects are pretty individual, though, so there are no firm guarantees....

Edit: You should probably talk to your prescriber about increasing the dose (if that's safe to do), augmenting it with something, or (especially if you haven't been on a lot of antidepressants) switching to something else.

I wouldnt say prozac was a weak AD. That award probably belongs to trazodone.
Prozac hits a bunch of stuff other than serotonin. And some people claim it increases their pain level and messes with their blood sugar.
Some of the things its approved for kind of make me wonder. I got really angry and irritable on it. =(
If it was me, I wouldnt go looking for the strongest SSRI. Id make a list of all the choices in that class and what their potential side effects are, and I would try them in order of perceived risk versus benefit.